The goal of this clinical core is to provide high numbers of samples of PBMC from subjects with acute / early phase HCV infection, allowing large-scale studies of immunologic parameters for investigators throughout the collaborative center. Funding of this core would allow continued identification of acute / early stage HCV infection in the Massachusetts State Prison system. Rationale includes the high number of young injection drug users entering the prison systems yearly, who are therefore at risk for HCV infection. The identification of acute HCV had traditionally been reliant on symptoms or laboratory abnormalities rather than exposure history, but our prior funding period established a system based on history-based risk factors to screen for early-stage HCV infection. This brief 1-2 minute questionnaire was designed to assist providers in identifying persons at risk for recent acquisition of HCV by injection drug use. The successful implementation in the MA state prison system identified a large number () of persons with acute HCV over a short period of time. In addition, longitudinal sample acquisition was greatly enhanced by this project. This represents the first systematic study of acute HCV among persons entering the prison system, providing critical information regarding the overall prevalence, clinical characteristics, and treatment outcomes of acute HCV in incarcerated individuals. Funding from this clinical core would allow continuation of this unique and valuable resource for both members of this Collaborative Center as well as allow collaboration with other groups examining questions not being addressed directly by this grant.